K&N Drop In Filters

ToeJam · May 15, 2004

I've put K&N filters in my past two cars, so I decided to buy one for my Sierra. With my other cars, I've definitely seen a difference with performance. Not so much with mileage, but with throttle response and less gear shifting on hills. So I was pretty surprised when I didn't feel any improvement with my K&N for my truck. Sometimes it almost felt like it was hurting my performace. I decided to test each one and track my results. Using the onboard trip computer, I got the following:

Stock paper filter

Miles driven - 2,500

Gallons of gas - 183

Average speed - 31 mph

Average MPG - 13.4

K&N filter

Miles driven - 1,600

Gallons of gas - 123

Average speed - 30 mph

Average MPG - 13.3

My truck had about 8,500 miles on it when I started this test. Overall I'm pretty surprised by the poor performance of the K&N. I've done the same road trips with both filters and the K&N seems to cause the truck to downshift earlier on hills than the paper filter. I've always like the fact that I can clean and re-use the k&N, but I think I'll be sticking with the paper filter from now on.

Rookie · May 16, 2004

interesting? Thanks

TROYROBO · May 16, 2004

i've had a k-n drop in in mine since i bought the truck--get between 17.5mpg hauling a car on dolly in summer with air on to 20.5 unloaded---gotta love my mpg it's got 5.3 with 3.42 gears and 2wd

03Bowtie · May 19, 2004

ToeJam,

Unfortunately, the results you are posting are NOT real world results. The computer in your truck that figures gas mileage is not very accurate. If you want "real world results", put your truck on a dyno and do at least 3 separate runs EACH with the paper filter and the K&N.

For gas mileage, I would calculate it this way to be more accurate:

At your next fill-up, write your odometer reading down, or reset your tripmeter. At the following fill-up, write it down again and divide the number of gallons into the number of miles driven. Do this 3-4 times and then average them together. This is a much more accurate estimate of MPG then the computer will give you.

It is very strange that the K&N is not giving you any MPG improvements, although I have heard that this can be the case. very rarely though.

kirkRHughes · June 4, 2004

I put the K&N FIPK set up on my 4.8 and I know I'm getting worse milage. I'm wondering if the reason might be that I get onto it more cause I like the sound,,,lol

Sierra04SLE · June 4, 2004

K&N and other low restriction filters do not benefit trucks. The high flow is not required until pushing 3500 to 4500 RPM and most of us do not do that, we use the low down torque of the engine. High flow filters, in my opinion only benefit high revving rice burners.

10 to 15% gains!!! At what RPM?

Check K & N's own claims

Horsepower is what gives you truck it's top end speed this is what their claims are usually based on.

Torque is what gives us the acceleration in the bottom half of the rev range.

Check the dyno results

More dyno results

More results

another result

Notice how these results are all for small high revving engines, I got tired looking for results for a large V8.

Want to look for yourself, here's the link to the index page.

The fuel saving claims may be relevant, but I would rather buy the gas than an aftermarket filter.

Robert

wonderl33t · June 16, 2004

I put the K&N FIPK set up on my 4.8 and I know I'm getting worse milage. I'm wondering if the reason might be that I get onto it more cause I like the sound,,,lol

ha. I put an FIPK on my 4.8L and I got the same city mileage, but +2 highway mileage.

jasonaspears · June 21, 2004

I have always had a K&N filter or FIPK for all of my cars and have noticed gains every time. As for trucks not be benefited by the increased airflow over stock, that is unbelievable and should definitely be edited. The best mods you can do for any internal combustion engine is getting it to breath (aka more air) and exhaust. You can tweak the rest of the motor all day long and if you don't have the right amount of airflow and exhaust, you ain't going to notice the ideal improvement. Just my $.02 but I love to be challenged. Convince me that the K&N FIPK is not worth anything on a truck with hard evidence and I will sell my FIPK right away...shoot, I'll give it away!

BTW, K&N should have Dyno results for virtually any vehicle that they have parts for, not just "rice burners"...check out the website and you will find a plethera of information...www.knfilters.com

theTANTALIZER · June 21, 2004

Does the FIPK system sucks hot air from the engine? I hear that is a negative thing. What I hear from my friends is that they just cut the bottom air box, opening a hole in the bottom which swallows more air and does the same performance as a 200 dollar FIPK would do.

mazingo · June 22, 2004

I was "curious" about how the amount of air flow might affect the performance, so i did my on little test. Though I dont recommend it, I took the filter out and ran down the road a few times. You could really hear the engine sucking in the air, and the throttle response was very noticable. Even with the PCM killing all the torque it could the truck still pulled harder. As I said I donot recommend driving with out a filter but we all know that k&n filters flow more than a 2" thick slab of paper. Just my observations.

jasonaspears · June 22, 2004

The K&N FIPK has a shield that goes around basically where the old airbox was. There is a mounting plate underneath the old airbox and this stays in place to form the base of the new intake "space" where the filter sits. I don't think that drilling through this on the stock box would help out at all since the restriction comes from the filter itself and the design of the tubing and duct work. The old filtering system is closed and pulls air from a couple small holes in the fenderwell area. In my opinion, this is going to be hotter air than the air moving through the engine compartment. True, the K&N is not a completely enclosed intake set up but is by far better than anything stock.

If you get a chance, find a dealer that has one of the K&N filter demonstration setups. It has a ping pong ball in a tube and has a small square spot for a filter. When you turn a little blower motor on, it sucks air through the filter hole. The demonstration is done using a standard paper filter which barely lifts the ball up the tube. Then you put on the K&N and the ball shoots straight to the top...you actually see the results of the increased air flow that just the filter makes.

theTANTALIZER · June 23, 2004

How much of a difference a K&N drop in filter vs a Cone FIPK in performance? Slight or marginal?

rcj_houston · June 24, 2004

I have noticed a dramatic drop in mileage from 14.7 to 12.9 since I have dropped in a K&N Air Filter in my 03 Tahoe with a 5.3 Someone on here commented that it could be my foot going harder since it is more peppy. I agree. It is more peppy and responsive, but with gas at $2 a gallon, I need mileage. I think I am going to take out the K&N and put the paper filter back until gas gets a bit cheaper. I do love the sound at full throttle, but lets all be honest. How often are you at full throttle when you still have 3 years of warrenty left????? Not I said the cat!

Cheers all...

jasonaspears · June 25, 2004

The difference should be pretty big. The FIPK actually replaces everything back to the throttle body and it is made to provide a lot of air and get it to the engine in as smooth of manner as possible. There is a lot of increased ability to move air with the new system as opposed the the OEM parts. A drop in filter is a fine replacement for the stock filtering components but once you can spend the $200 or so for a FIPK, you won't regret it. Yes, your mileage may get worse but just like rcj_houston said, it is probably due more to the increased weight of the right foot.

A wise friend of mine once told me that for a Christian, the very last thing to be saved is his right foot!

fastdrvr23 · June 25, 2004

The difference should be pretty big. The FIPK actually replaces everything back to the throttle body and it is made to provide a lot of air and get it to the engine in as smooth of manner as possible. There is a lot of increased ability to move air with the new system as opposed the the OEM parts. A drop in filter is a fine replacement for the stock filtering components but once you can spend the $200 or so for a FIPK, you won't regret it. Yes, your mileage may get worse but just like rcj_houston said, it is probably due more to the increased weight of the right foot.

A wise friend of mine once told me that for a Christian, the very last thing to be saved is his right foot!

Jason is right on. I've run both in my truck and can tell a big difference in the two. With the drop-in, my mileage on the highway went up about 1MPG, with the FIPK I gained 2 or 2.5MPG on average. The FIPK has much better throttle response, and a little more mid range and top end. The wester's tune probably helps alot too, but I am very pleased with my FIPK.

One other thing, I am running a "Drycharger" to make sure it doesn't take in any water, this supposedly cuts down on flow a small amount.... I surely can't tell. I went back to the stock airbox and paper filter when I brought the truck in for warranty work a few weeks ago, and it felt like a totally different vehicle, especially at highway speeds.